Prehistoric humans reportedly recognized the dangers of inbreeding and created networks for mating in order to avoid it, researchers say. The new report that is published in the journal Science claims there is evidence indicating that a highly sophisticated mating network may have been involved in early human procreation. The researchers inferred that prehistoric man might have deliberately avoided inbreeding.

During the Upper Paleolithic period, modern humans traveled from Africa into Eurasia. Genetic information found in the remains of these early people suggests that they deliberately looked for mates outside of their immediate family units. An international team led by experts from the University of Cambridge and the University of Copenhagen sequenced the genomes of four early human beings from an Upper Paleolithic site in Russia. Sunghir, the site where the remains were located, is reported to have been inhabited by the humans 34,000 years ago, according to Science Daily.

The individual prehistoric humans buried at Sunghir are believed to have lived at the same time. The researchers say that the early humans were buried together. Genetically, they couldn’t have been more closely related than second cousins, reportedly indicating a lack of inbreeding. The researchers say that two children had been buried together, head-to-head in one of the graves. The genomes of those ancient children indicate that even these children were not immediately related, according to a University of Cambridge press release.

“What this means is that even people in the Upper Paleolithic, who were living in tiny groups, understood the importance of avoiding inbreeding,” Professor Eske Willerslev, senior author on the study, inferred. “The data that we have suggest that it was being purposely avoided.

“This means that they must have developed a system for this purpose. If small hunter-gatherer bands were mixing at random, we would see much greater evidence of inbreeding than we have here.”

Remarkably, jewelry and objects included in the graves also suggest that these early humans may have had sophisticated ceremonies and rules associated with mating, according to the press release.

“The ornamentation is incredible and there is no evidence of anything like that with Neanderthals and other archaic humans,” Willerslev said. “When you put the evidence together, it seems to be speaking to us about the really big questions; what made these people who they were as a species, and who we are as a result.”

“Most non-human primate societies are organized around single-sex kin where one of the sexes remains resident and the other migrates to another group,” Professor Marta Mirazon Lahr from the University of Cambridge said. “At some point, early human societies changed their mating system into one in which a large number of the individuals that form small hunter-gatherer units are non-kin. The results from Sunghir show that Upper Paleolithic human groups could use sophisticated cultural systems to sustain very small group sizes by embedding them in a wide social network of other groups.”

No current data indicates that Neanderthals avoided inbreeding. Genome sequencing of one Neanderthal found in the Altai Mountains showed evidence of inbreeding. Professor Martin Sikora from the University of Copenhagen said that it should be noted that the Altai Mountain Neanderthal may have lived in an isolated group. More genome data is needed to know for sure that the inbreeding evidence researchers found from this one individual is indicative of widespread Neanderthal inbreeding.

Did our prehistoric human ancestors know the dangers of inbreeding? The authors of the prehistoric inbreeding study indicate that they believe that may be the case. The lack of inbreeding in prehistoric humans might be one reason that early man persisted, while Neanderthals died out.